Kovar is a nickel-cobalt ferrous alloy designed to be compatible with the thermal expansion characteristics of borosilicate glass (~5×10^-6 /K between 30 and 200°C, to ~10×10^-6 /K at 800°C) in order to allow direct mechanical connections over a range of temperatures. It finds application in electroplated conductors entering glass envelopes of electronic parts such as vacuum tubes (valves) and some lightbulbs. Kovar is composed typically of 29% nickel, 17% cobalt, 0.2% silicon, 0.3% manganese, and 53.5% iron (by weight). General Name, symbol, number nickel, Ni, 28 Chemical series transition metals Group, period, block 10, 4, d Appearance lustrous, metallic and silvery with a gold tinge Standard atomic weight 58. ... For other uses, see Cobalt (disambiguation). ... Ferrous in chemistry is a term used for the iron with an oxidation number +2. ... An alloy is a homogeneous hybrid of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ... In physics, thermal expansion is the tendency of matter to increase in volume or pressure when heated. ... It has been suggested that Kimax be merged into this article or section. ... Electroplating is the the coating of an electrically conductive item with a layer of metal using electrical current. ... In electronics, a vacuum tube (American English) or (thermionic) valve (British English) is a device generally used to amplify a signal. ... The incandescent light bulb uses a glowing wire filament heated to white-hot by electrical resistance, to generate light (a process known as thermal radiation). ... General Name, symbol, number nickel, Ni, 28 Chemical series transition metals Group, period, block 10, 4, d Appearance lustrous, metallic and silvery with a gold tinge Standard atomic weight 58. ... For other uses, see Cobalt (disambiguation). ... Not to be confused with Silicone. ... General Name, symbol, number manganese, Mn, 25 Chemical series transition metals Group, period, block 7, 4, d Appearance silvery metallic Standard atomic weight 54. ... For other uses, see Iron (disambiguation). ...

External links

• Kovar specification sheet